A hard disk drive includes a head disk assembly and a printed circuit board attached to a disk drive base of the head disk assembly. Referring now to FIG. 1, the head disk assembly 10 includes at least one disk 11 (such as a magnetic disk, magneto-optical disk, or optical disk), and a track seeking/track following actuator 12, and at least one head gimbal assembly HGA that includes a head 14 and a suspension assembly 13. During operation of the disk drive, the track seeking/track following actuator 12 must rotate to position the head 14 adjacent desired information tracks on the disk 11. An arrow on disk 11 indicates the direction of disk rotation in FIG. 1. Track seeking/track following actuator 12 may be a rotary actuator driven by a voice coil motor. The disk 11 includes an information storage media, such as, for example, a hard magnetic layer protected by a thin overcoat layer and supported by a substrate and various underlayers.
The head 14 comprises a body called a “slider” that carries a magnetic transducer on its trailing end. The magnetic transducer comprises a writer and a read element. The writer may be of a longitudinal or perpendicular design, and the read element may be inductive or magnetoresistive. The transducer is supported in close proximity to the magnetic disk by a hydrodynamic air bearing. As the motor rotates the magnetic disk, the hydrodynamic air bearing is formed between an air bearing surface of the head and a surface of the magnetic disk.
As the information storage capacities of hard drives are increased, the information tracks thereon become more closely spaced. Accordingly, accurate positioning of the transducer with respect to the information tracks becomes increasingly important to ensure accurate reading and writing of the data stored in the information tracks.